Ah ok thanks! The qemu command line i was using is here: `qemu-system-x86_64 -chardev stdio,id=seabios -device isa-debugcon,iobase=0x402,chardev=seabios -m 2G -smp 2 -M pc -vga none -usbdevice tablet -cpu host,-invpcid,-tsc-deadline,check -drive 'file=/path/to/image.bin,index=0,media=disk,cache=unsafe,format=raw' -enable-kvm -device vfio-pci,x-igd-opregion=on,host=00:02.0,id=hostdev0,bus=pci.0,addr=0x2,rombar=0 -device 'virtio-net,netdev=eth0' -netdev 'user,id=eth0,net=10.0.2.0/27,hostfwd=tcp:127.0.0.1:9222-:22'`
It didn't work, but now at least I know why: [ 0.316117] i915 0000:00:02.0: No more image in the PCI ROM [ 0.316261] [drm] Failed to find VBIOS tables (VBT) If I can expose the VBT to the VM maybe it will work :) On Fri, May 24, 2019 at 2:19 PM Alex Williamson <alex.william...@redhat.com> wrote: > > On Fri, 24 May 2019 14:10:03 -0700 > Micah Morton <mort...@chromium.org> wrote: > > > On Fri, May 24, 2019 at 12:50 PM Alex Williamson > > <alex.william...@redhat.com> wrote: > > > > > > On Fri, 24 May 2019 11:12:41 -0700 > > > Micah Morton <mort...@chromium.org> wrote: > > > > > > > I’ve been working with an Intel Chrome OS device to see if integrated > > > > GPU passthrough works. The device is a 7th Generation (Kaby Lake) > > > > Intel Core i5-7Y57 with HD Graphics 615. So no discrete GPU. I think > > > > iGPU passthrough should work on this device. > > > > > > > > Initializing the graphics hardware has proven to be the trickiest part > > > > in all of this, and I have a question I thought someone on this list > > > > might be able to answer: > > > > > > > > Why does vfio enforce that I _need_ a VGA rom to be available in order > > > > to boot the guest in legacy passthrough mode > > > > (https://github.com/qemu/qemu/blob/master/hw/vfio/pci-quirks.c#L1616)? > > > > > > "Legacy" mode is largely about setting up components to make the VGA > > > ROM work. Some of the components of legacy mode are faking stolen > > > memory (which really only works for the ROM, not the OS driver), adding > > > the LPC bridge (not sure of the OS driver dependency on this, but I > > > think it can be manually added if needed), and adding the OpRegion > > > (which can also be manually added). If you only care about OS level > > > graphics initialization then you probably only need the OpRegion > > > support, which Intel vGPU also needs but Intel can't provide a > > > consistent story about how it should work. So why do you think you > > > need legacy assignment mode? Granted UPT mode is just about a > > > forgotten ideal at Intel, but legacy mode doesn't really solve the > > > stolen memory dependencies for anyone but the VGA ROM. > > > > Ah ok. Yeah I have no reason to think I need "legacy" mode apart from > > the fact that I wanted the GPU to be the "primary and exclusive > > graphics device in the VM". Is the only alternative UPT mode, which > > "does not support direct video output" > > (https://android.googlesource.com/platform/external/qemu/+/emu-master-dev/docs/igd-assign.txt#14)? > > So I can definitely pass through the device to the guest and get the > > i915 driver in the guest to attach to it on some level: > > > > ~ # lspci -nnk (in the guest) > > ... > > 00:02.0 VGA compatible controller [0300]: Intel Corporation Device > > [8086:591e] (rev 02) > > Subsystem: Intel Corporation Device [8086:2212] > > Kernel driver in use: i915 > > > > I guess the question for me now is whether I need OpRegion support in > > the guest (or anything else) for the guest driver to successfully use > > the GPU (I just see a black screen right now and haven't yet enabled > > much in the way of meaningful logs for i915). Do you have any pointers > > to resources on how the OpRegion can be added? Or am I better off > > contacting Intel engineers? > > If you're using QEMU by command line, just add x-igd-opregion=on to the > set of device parameters for the vfio-pci device. libvirt does not > provide a supported way to add this (the 'x-' prefix indicates an > experimental option and is used here because it's rather a hack), but > you can use <qemu:arg> elements to pass it, such as documented here: > http://vfio.blogspot.com/2016/09/passing-qemu-command-line-options.html > It's entirely possible that this alone will be enough to light up the > display. Thanks, > > Alex _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users
